My model of the world, as levels of abstration
<pre>
    Physics is fundamental*                            |
                                                       | Mathematics
    Chemistry is an abstraction of physics             | pervades
                                                       | all these
    Biology is an abstraction of chemistry             | things
                                                       |
    Sociology & psychology are abstractions of biology | Computer
                                                       | science
    Economics is an abstraction of sociology & psych.  | impacts
                                                       | all these
    Engineering is built on several of the preceding   | things
</pre>
*(today) Maybe tomorrow physics will be based on computer science
principles (e.g. it will be agreed that the universe is a cellular
automaton) and the position of CS in the abstraction hierarchy will
change.